1. Field of the Invention
The present invention relates to a control apparatus-integrated generator-motor that is mounted to a vehicle.
2. Description of the Related Art
In recent years, reductions in CO2 emissions are being sought in order to prevent global warming. Reduction of CO2 in automobiles means improving fuel consumption performance, and examples of proposed solutions include idling stop when vehicles are stationary, energy regeneration during deceleration, etc. In order to achieve that, automotive generator-motors have been proposed in which a starter motor and a charging generator are integrated. With these conventional automotive generator-motors, a vehicle engine can be restarted by the generator-motor, which is connected to an inverter, after automatic idling stop.
In addition, a technique has been proposed concerning generator-motor idling stop control in which an automatic engine stopping operation is inhibited and engine running is continued even if conditions for performing the automatic engine stopping operation have been met, if it is ascertained that temperatures in respective switching elements in an inverter might exceed a permissible temperature level due to an engine restarting operation after the automatic engine stopping operation (see Patent Literature 1, for example). In this conventional technique, because the subsequent engine restarting operation is avoided if it is suspected that the temperatures in the respective switching elements in the inverter might exceed the permissible temperature level due to the engine restarting operation after the automatic engine stopping operation, the switching elements are prevented from reaching an impermissibly high temperature state during the engine restarting operation.
Patent Literature 1: Japanese Patent Laid-Open No. 2004-156589 (Gazette)
However, inhibiting the engine stopping operation and continuing engine running even if conditions for performing the automatic engine stopping operation have been met if it is ascertained that the temperatures in the respective switching elements in the inverter might exceed a permissible temperature level, as in the conventional technique mentioned above, means that fuel consumption is poor while the automatic engine stopping operation is being inhibited, at the very least. There is a possibility that such conditions may arise frequently in summer, and one problem has been that deterioration in fuel consumption and increases in exhaust gases may occur in no small measures.
In a control apparatus-integrated generator-motor in which an inverter, etc., is disposed integrally on an axial end surface or an outer circumference of the generator-motor, a unique phenomenon also occurs whereby the temperatures of the switching elements of the inverter start to increase immediately during the automatic engine stopping operation during idling stop because heat is received during a power generating operation before the automatic engine stopping operation due to thermal conduction, etc., from an armature winding, which generally has the highest temperature, and because a forced cooling action by fans on the generator-motor is absent during the automatic engine stopping operation. Thus, it has been difficult to determine whether or not the temperature of the switching elements will exceed the permissible temperature level due to the engine restarting operation after the automatic engine stopping operation when the above conventional technique is applied to control apparatus-integrated generator-motors since there are unique temperature increases in these switching elements. Even if the above determination were to become possible, the frequency with which the automatic engine stopping operation is inhibited would increase because the frequency with which the temperature of the switching elements is determined to be in excess of the permissible temperature level would no doubt increase, and in the end, the issue would remain that problems such as deterioration in fuel consumption and increases in exhaust gases are further exacerbated.